Incidence and associations of single umbilical artery in prenatally diagnosed malformed, midtrimester fetuses: a review of 62 cases.

The absence of one umbilical artery (SUA) is the most common malformation of the umbilical cord. It may accompany other abnormalities or occur as an isolated defect. We examined 885 fetuses, terminated following the prenatal diagnosis of serious or lethal malformations between April 1977 and March 1989, for the presence of SUA. We found 62 cases of SUA. This represents an incidence of 7.01% (62/885). The most common abnormalities found in association with SUA were: (1) multiple malformations (8/11 cases, SUA incidence = 72.7%), (2) ADAM complex (7/14 cases, SUA incidence = 50.%), (3) multicystic renal dysplasia (5/20 cases, SUA incidence = 25.%), and (4) Potter sequence (5/21 cases, SUA incidence = 23.8%). These associations have not been documented previously. In 6 fetuses the Meckel syndrome was diagnosed, and SUA was present in 2 of these. Therefore, SUA may represent an additional anomaly in Meckel syndrome that has not been reported previously.